A number of recent reports suggested that Guardiola could be on his way out of Bayern this summer after he received criticism following the Bavarians' Champions League exit at the hands of Real Madrid in the semi-finals.
Nevertheless, Nadal - who played alongside Guardiola at Barca between 1991 and 1999 - has insisted his former team-mate is happy with life at his current club.
"Is Guardiola happy at Bayern? Absolutely," Nadal was quoted as saying by the official Bundesliga website.
"After leaving Barcelona, it was very important to Pep to join the right club. One that matched his own standards and aspirations. And Bayern are one of the best football addresses in the world game.
"I got to know Pep as a fairly straightforward kind of guy. He always demanded a lot of himself, especially at work. Although football isn't just his job, he loves it and he'll leave no stone unturned in the pursuit of success.
"We're close friends, he's a good bloke, tapped into his emotions and a family man. For all the success he's had, he's remained human."
Guardiola guided Bayern to the domestic double in his first season at the Allianz Arena.